The present invention relates to a semiconductor processing apparatus, more specifically, to a processing solution supply apparatus for supplying a processing solution onto a substrate to be processed such as a semiconductor wafer or the like.
Conventionally, in a processing solution supply apparatus for supplying a processing solution onto a substrate to be processed, a container storing the processing solution and a nozzle placed near the substrate to be processed are connected with each other by a supply pipe, so that the processing solution stored in the container is sent to the nozzle by a pump which is provided at a midpoint in the supply pipe.
FIG. 14 is a schematic diagram of a processing solution supply system used in a conventional-type processing solution supply apparatus.
As shown in FIG. 14, in a processing solution supply system 214, a processing solution tank 201, a liquid end sensor 203, a supply pump 204, a filter 205, a discharge pump 206, and a nozzle 202 are stacked in this order, and these adjoining components are connected with each other by a supply pipe 207. To the filter 205 attached is a vent pipe 208 leading to a waste solution tank (not shown).
A purge pipe 209 is attached to the discharge pump 206 on the downstream side in a direction of movement of the processing solution. This purge pipe 209 is connected to a T-shape branch pipe 213 which is attached to a supply pipe 207b between the processing solution tank 201 and the liquid end sensor 203 so as to allow the processing solution which has passed through the purge pipe 209 to join the supply pipe 207b.
By the way, in the processing solution supply system 214 having a configuration in which the processing solution tank 201 and the nozzle 202 are linked together by the long supply pipe 207 as shown in FIG. 14, bubbles often form in the supply pipe 207, and if the bubbles are left as they are, the amount of the processing solution discharged from the nozzle 202 onto the substrate to be processed, such as a wafer, varies, resulting in a danger of reducing quality of the wafer. Therefore, the processing solution supply system 214 shown in FIG. 14 includes a bubble-removing mechanism.
More specifically, in the case where air enters in the supply pipe 207 such as the case where a processing solution is newly poured into the processing solution tank 201 and the case where a filter module in the filter 205 is exchanged for another and the processing solution is newly allowed to flow, the supply pump 204 is operated in the state where a vent valve 211 of the vent pipe 208 is opened at the time of start of the supply of the processing solution to send the processing solution which is pumped up from the processing solution tank 201 to the filter 205. Into the filter 205, a processing solution containing a large amount of bubbles is first sent, the amount of bubbles gradually decreasing, and finally a processing solution without bubbles is supplied. For this reason, the processing solution containing bubbles is disposed of to a waste solution tank (not shown) through the vent pipe 208.
Here, there is a disadvantage that the processing solution is all disposed of when the supply pump 204 is started with the vent valve 211 being opened, resulting in a big waste of the processing solution.
Further, bubbles often form in the supply pipe 207 also during the normal operation of discharging the processing solution from the nozzle 202 onto the wafer W, and in that case, a purge valve 212 of the purge pipe 209 which is connected to the discharge side of the discharge pump 206 is opened to send the processing solution containing bubbles to the purge pipe 209 side.
However, since the purge pipe 209 is connected to the T-shape branch pipe 213 provided at the supply pipe 207b between the processing solution tank 201 and the liquid end sensor 203, there is a disadvantage that the processing solution containing bubbles recirculates in the supply pipe 207, thereby interfering the supply of an accurate amount of the processing solution.